Do Honey Bees Drink Water?

One warm, sunny afternoon last summer I was at the local beach with my son and our dog. While the two of them were messing in the water, I lazily indulged in one of my favourite past times. Bee spotting. First, I watched bumblebees and honeybees working their way through the masses of newly opened flowers on the wild goji berry bushes growing along the shore. I remember thinking that we ought to get a good crop of berries in the autumn. And then how lucky we are to have this unusual treasure so close to home.

When I had my fill of bees and flowers, I sat down in the sun to watch boy and beast’s boisterous caper. And lo and behold, on my lap landed a honeybee. She took in her surroundings for a brief moment, then purposefully walked off me. She walked onto the rock I was sitting on and headed straight towards the water’s edge. There she extended her proboscis and began drinking the seawater. And it struck me that this was not the first time I had seen bees drinking seawater.

I often collect seaweed for the vegetable garden. And even though my bees are within a short distance of the harbour, every time I bring home a load of fresh seaweed it is only a matter of minutes before the first bee comes to check it out. She will go back home and raise the alarm within the hive. And soon enough there is usually a steady stream of very enthusiastic winged visitors to the freshly offloaded pile.

How Honeybees Use Water

In this post, we will look at bees and their relation to water and moisture in the hive. Mainly how bees use water, its collection, water quality and preference. I will not put a lot of emphasis on the issue of condensation and moisture in relation to overwintering. As winter moisture is so closely related to temperature, it should be examined in conjunction with winter set up of hives. Including insulation, temperature, and ventilation. More on that here: Beehive Insulation Condensation and Ventilation

Like all other animals, honeybees need water to survive. They use it to dilute honey stored in the hive. Copious amounts of water is used up producing brood food to feed the developing larvae. It is also used to cool the hive during periods of extreme heat. Water is often talked about in terms of the water economy of a hive. It is thought that a colony can go through up to a litre of water in a day. Especially if water is needed for cooling purposes. We also need to consider the water needs of individual bees. Or more precisely, the potential role that thirst might have in triggering behaviours such as water collection and water distribution.

Bees Use Water to Dilute Honey

In order for bees to use honey from the hive, they will mix honey with water to dilute it. The reason that honey is not stored with a higher moisture content initially is that it would ferment and spoil. Hence the need to first reduce the water content of nectar from about 80-95% to below 20%. And then store it, and when needed increase its water content to be able to consume it. The brood food produced by hypopharyngeal glands of young worker bees contains about 70% water. Open brood is quite hungry and its regular and frequent feeding increases the water use of the colony. Therefore, the more brood food that is produced, the more water is needed to sustain the colony.    

Bees use water to cool the hive

During periods of heat stress, honeybees will use water to cool the brood nest of the hive. During brood rearing the temperature in the brood nest is around 35 degrees Celsius.

Water is an ideal cooling medium because it has the ability to absorb a lot of energy (heat) before turning into vapour. The in-house worker bees acting as water receivers will smear droplets of water inside the cell walls of cells with open brood in them, and on sealed brood. Other worker bees will then fan their wings creating a flow of warm air directed towards the water droplets. This causes the droplets to turn into vapour. As the water evaporates, it brings with it the heat from the airflow thus cooling the brood area. If it were not for this very clever use of water as a coolant, the brood would be at risk of over-heating, and in extreme conditions drying out.   

Where Does the Water Come From?

Water is available to the bees from three main sources: Nectar, condensation and water brought in by water collectors. In our climate, and throughout most of the rest of the world, honeybees do not store water in the hive. Bees have been seen to store water in regions that suffer extreme heat and drought. Hence, one will have to conclude that it is a local adaptation precipitated by extreme conditions. However, at the end of a day of water stress, or hive thirst, our bees can, and often will, hold water reserves in their honey crop. The honey crop is not ideal for long term storage, so this water is used up within a matter of hours.

Some Bees are Specialized Water Collectors

Although the nectar brought into the colony by the nectar foragers contains a lot of water, the duty of water collection falls on bees whose sole job is to collect water. Studies have shown that individual bees show preferential behaviour towards liquids with various degrees of sweetness. It is thought that this preference for different levels of sweetness is genetic. If this is the case, water collectors are destined to become water collectors in the same way as nectar collectors are to become nectar collectors.

The water collectors are highly specialised and once they have found a good water source, they show incredible site fidelity. They will often return to the exact spot to collect water. In the energy economy of the individual bee this makes sense of course, why waste energy looking for new water sources when the most pressing need is to quickly get water back to a thirsty hive.  

(Just a little scientific sidenote: many things such as preference for sweetness, salinity, minerals, etc, are studied by measuring the proboscis extension reflex (PER) of the bee. The proboscis extension reflex is an integral part of the bees’ feeding behaviour. When the antenna touches a liquid, the proboscis, or tongue, automatically sticks out to taste it. The bee will then either drink, or not drink, depending on the content of the liquid. Measuring the PER is a simple but very effective way of determining the individual preferences of honeybees and other insects.)

Water Collection

Water collectors are older bees, often 20 days and older, with a preference for less sweet liquids. The water collection of a hive is directly linked to its current water needs. When there is a need for water in the hive, the bees will first use up whatever water is available in their honey crops, and when this water has been used up, the water collectors are sent out. When water is not needed, water collecting bees have been observed to be either walking around in the hive or otherwise resting or idle.

Triggers For Water Collection

What triggers water collection to commence has been studied extensively by Thomas Seeley. He has shown that water collection is a complex process most likely triggered by one of two occurrences, or possibly a combination of the two. The first is the begging behaviour of worker bees towards water collectors. The second is personal thirst of the individual bee.

When a colony experiences water stress, and the bees have used up the water in their crops, the only way to increase the amount of water in the hive is to get it externally. The worker bees have been seen to start begging the water collectors. This behaviour increases steadily the greater the water stress becomes. The begging is done by the worker bee walking up to the water collector. She then extends her proboscis in front of the mouthpart of the water collector. Having given up all the water in her own crop, the water collector has no water to offer the beggars, and she is also likely to herself feel thirst or that there is an increasing need of water both individually and for the hive.

The water collector will then set out to get water. When she gets to her chosen watering hole, she will extend her proboscis and fill up her honey crop with water. Although the honey crop can hold up to 100 milligrams of nectar or water, a water collector will often collect about 25-40mg per trip. She will then return to the hive to be offloaded before she goes out again.

Unloading the Water in the Hive

The water collectors usually do not go very far inside the hive with their load. They are often relieved of their burden close to the entrance by a water receiver. The water receivers are middle aged bees, about 10-20 days old. There has not been a lot of research into the water receivers, their specific genetics and preferences. However, there is a hypothesis that like water collectors, they too have a preference for less sweet liquids. Therefore it is entirely possible that it is these bees who, when older, will become water collectors.

When offloading, the water collector does not appear to know which bees are water receivers. As a result, she will either offer water to other bees to taste, or she will be asked (begged) for a taste from the worker bees. The water is then passed from collector to receiver through trophallaxis, tongue to tongue. The receiver will then proceed to distribute it within the hive. She will walk through the hive, offering water to other worker bees or being asked. She will often stop to look into cells containing open brood and smear water inside the cell walls if she recognises that it needs cooling.

Stopping Water Collection

When the water needs of the hive has been satisfied, the water collection decreases. The question of how the water collectors know when to cease collecting has been studied in detail, with particular attention to the interactions between water collector and water receiver. It has been noted that as the water needs decreases, a few things happen.

First, the water receiver will experience more unloading refusals. This is where she offers the worker bees a taste of what is in her crop, and if the bee that tastes it is not interested, she will proceed to offer it to other bees. Unloading refusals are common, as some workers are looking for nectar and not water, but for the water collector the number of refusals increase dramatically as the water needs of the hive diminishes. Second, the length of time it takes for each offload increases, and third, the begging slows to a halt. 

What Water do Bees Pefer?

Honeybees are attracted to water they can smell. Or rather they are attracted to water that contains things that they can smell, such as minerals. This could be one of the reasons why, despite field experiments showing that bees actually prefer clean water to dirty water, they are drawn to collect water from water sources that are, shall we say, less than appetizing or even hygienic.

Filthy, dirty, chlorinated and sea water simply smell more than its clean, fresh, filtered, or pristine counterpart. Another reason would be that bees need certain minerals that are lacking in their diet, and they get those from water. It has been recorded, however, that foragers mark unscented water sources with their Nasonov pheromone, which would lead other bees to be able to find the source. Once a bee has found and become attached to a water source, smells or markers become less important as she is then able to locate the site by other means. She will return to the site when needed as long as there is a constant supply of water there. Like nectar foragers, water collectors will perform waggle dances to indicate the location of a water source.

Salt and Other Minerals

There have been both field tests and lab experiments done on bees and their water preferences. In the field tests, water from different sources and with different substances and minerals added have been laid out side by side, and the water levels have then been monitored to see which solutions are most/least popular. Among other things, these tests have shown that bees do like clean, filtered water and will often chose it ahead of dirty water or chlorinated water if given a choice (however being able to locate it due to its lack of smell may be an issue). The tests also show that honeybees display a preference for water with some degree of sodium (Na) in it. 

In the lab experiments, bees have been given water with different minerals and different amounts of these minerals, and their proboscis extension reflexes measured and analysed. These experiments concluded that bees prefer water with 1.5-3% Sodium and 1.5% Magnesium. Water containing only the lowest concentrations of Potassium and Phosphate were acceptable to the bees. In the same experiments, known sources for water collection by honeybees were tested and shown to contain a wide range of salt concentrations. Further studies have also indicated that individual bees have different and very wide-ranging sodium preference. It is suggested that some bees may specialize in collecting water with high salt concentrations.

Water Stress and Humidity

When we hear about water stress, it is often mentioned in relation to the thirst of a hive, or a hive needing water for cooling or feeding. When there is a lack of water in the hive, water collection commences, for long term water stress, brood rearing decreases.

Much of the literature available deals with the issue of water stress in the same way. How honeybee colonies collect and use water. This, I feel, is often not the first thought that comes to mind when us Irish beekeepers think about water and bees. Our bees seldom deal with extreme heat. Neither do they experience long, cold spells where they cannot go outside to collect water like they do in many other regions. We think about water stress in terms of having too much, not too little, water. Hence, we are often worried about condensation and moisture in our hives, particularly during the winter months.

The humidity within the hive varies according to the temperature and the activity/-ies carried out. Hot air can hold more water than cold air. Different areas of the hive also have different moisture requirements. The brood area with open brood requires high humidity, but the area where nectar is dried out requires low humidity. If the humidity in the brood area is too low, this will inhibit the hatching of eggs into larvae. The ideal humidity for brood rearing is somewhere between 50-60%. When the colony is not rearing brood, the humidity in the hive is relative to the temperature.

Water in Winter

Having too much moisture in the hive during winter is something that worries many beekeepers. Especially as excess moisture provides ideal conditions for fungi and mould. As the bees consume the honey or sugars in fondant, they gain energy and free up water. One kilo of sugar or honey will generate approximately 600ml of water after consumption. The bees can get rid of this water either by breathing, defecating, or recycling it into brood food. In the winter, when the bees cannot leave the hive for cleansing flights, the only two options available to them is breathing and converting it into brood food. The need to get rid of excess water may be one of the reasons why we often see brood rearing in our hives during January and February, which are often the coldest months.

Winter Cluster

When clustered, the centre of the cluster releases a lot more water than the outer layers of the cluster. The dehydration of the bees in the centre of the cluster might be what motivates the bees to regularly switch places within the cluster throughout winter. The water that is released through exhalation will rise to the top of the hive. There it will condense if the top of the hive is not insulated. Or be fully or partially absorbed if using a quilt box or other porous or absorbent material. If the top or roof of the hive is insulated, the vapour will spread under the crown board. It will then condense on the walls of the hive. There it will drip down onto the floor or through the open mesh floor.

Ventilation and insulation in winter

If the hive is top-ventilated the vapours will fully or partially leave the hive depending on the airflow. If the top of the hive is uninsulated, there is a high risk that the vapour will condense on the crown board above the cluster. The cold water from the condensation could then drip down onto the cluster. Such drips can chill both bees and any brood present. This should be avoided, and the best way of doing so is by insulating the top of the hive. Some beekeepers advocate providing top ventilation. If doing so, make sure you do not create a draught if the hive is also ventilated from the bottom. Also be careful with through draughts if you have a large opening at the entrance. To read more about bees in winter including how to properly set up for ventilation and insulation, read this blog: Beehive Condensation, Insulation And Ventilation

In our climate, the bees can access water outside of the hive for most of the year. If the need arises, they can also utilise the water from condensation.

Finally, and to return to my bee spotting, I would urge you to watch carefully where your bees are collecting water. If you get to know their favourite watering holes, you will be able to learn a lot from their behaviour. You will know when the water need is the highest. You will also be able to tell, with an impressive degree of certainty, when a nectar flow stops and starts.

I hope you enjoyed reading this post, please feel free to comment below. Read more here about how to make your own Water Drinker for Bees and other Insects in your garden.

/Hanna

Hanna Bäckmo

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